New answers tagged group-by
0
votes
Conditional selection in a GROUP BY clause
Using FIRST_VALUE the query would be a little simpler.
Using the following data example
CREATE TABLE cities (
country VARCHAR(20),
city VARCHAR(20),
population INT
);
INSERT INTO cities ...
- 3,685
0
votes
Conditional selection in a GROUP BY clause
You need to join the country and population as follows
SELECT A.country,A.city,A.pop population FROM
(SELECT country,city,population pop FROM cities) A INNER JOIN
(SELECT country,MAX(population) pop ...
- 181k
1
vote
Accepted
Why use $group / group_by instead of multiple requests?
why perform a query involving $group which in principle processes each document sequentially
This is not necessarily true. The database engine is designed to be optimized for such type of operations, ...
- 34.1k
1
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Adding subtotals using GROUPING SETS
This is a translation of your description into SQL:
... GROUP BY GROUPING SETS ((store, department, gender), (store))
- 45.8k
1
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Select first row of a particular group with one attribute selected as 0 while all other rows should be selected as is
I am currently doing the above by breaking/splitting my queries. Is it possible to do this in a single query?
Sure, you can use a window function in a subquery to order the rows within a grouping (...
- 34.1k
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